Mobile terminal charging device and vehicle equipped with same

ABSTRACT

A controller of a mobile terminal charging device compares a resonance frequency or a resonance voltage of each of a plurality of foreign object detection coils with a reference resonance frequency or a reference resonance voltage of each foreign object detection coil, stored in a memory, corresponding to a position of a charging coil. The controller performs a safety operation on the basis of a comparison result.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. national stage application of the PCT International Application No. PCT/JP2014/005484 filed on Oct. 30, 2014, which claims the benefit of foreign priority of Japanese patent applications 2013-245749 filed on Nov. 28, 2013, 2013-227925 filed on Nov. 1, 2013 and 2013-239492 filed on Nov. 20, 2013, the contents all of which are incorporated herein by reference.

1. Field of the Invention

The present invention relates to a mobile terminal charging device used to charge a mobile terminal such as a mobile phone, and a vehicle equipped with the same.

2. Description of the Related Art

Functions of a mobile terminal such as a mobile phone have been considerably advanced, and thus power consumption thereof has also been increased. Therefore, charging the mobile terminal is required to be performed at any location including the inside of a vehicle, but, as a trend in recent years, a mobile terminal charging device which can perform so-called noncontact charging without using a cable has been attracting attention.

In other words, the mobile terminal charging device includes a support plate whose surface side serves as a mobile terminal placement portion, a charging coil movably provided to oppose a bottom side of the support plate, driving means for moving the charging coil so as to oppose the bottom side of the support plate, and a controller connected to the driving means and the charging coil.

The support plate is provided with a plurality of detection coils as position detection means for detecting a position of a mobile terminal installed on an upper surface of the support plate (for example, PTL 1).

CITATION LIST Patent Literature

PTL 1: Japanese Patent Unexamined Publication No. 2009-247194

SUMMARY OF INVENTION

The present invention provides a mobile terminal charging device preventing an increase in the temperature of a foreign object, even in a case where there is the foreign object, such as a coin, on an upper surface of a support plate.

According to an aspect of the present invention, there is provided a mobile terminal charging device including a support plate in which a mobile terminal placement portion is provided on a front surface side thereof; a charging coil; a driver; a controller; a memory connected to the controller; and a plurality of foreign object detection coils. The charging coil is movably disposed in a state of opposing a rear surface side of the support plate. The driver can move the charging coil on the rear surface side of the support plate. The controller is connected to the charging coil and the driver. The plurality of foreign object detection coils are provided on the support plate and are connected to the controller. The memory stores a reference resonance frequency or a reference resonance voltage of each foreign object detection coil for each location where the charging coil is present. The controller compares a resonance frequency or a resonance voltage of each of the plurality of foreign object detection coils with the reference resonance frequency or the reference resonance voltage corresponding to a position of the charging coil stored in the memory. The controller performs a safety operation on the basis of a comparison result.

With the above-described configuration, it is possible to prevent an increase in the temperature of a foreign object, even in a case where there is the foreign object, such as a coin, on an upper surface of a support plate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating a state in which a mobile terminal charging device according to an exemplary embodiment of the present invention is provided inside a vehicle.

FIG. 2 is a perspective view illustrating the mobile terminal charging device according to the exemplary embodiment of the present invention.

FIG. 3 is a perspective view illustrating a state in which a mobile terminal is installed on the mobile terminal charging device illustrated in FIG. 2.

FIG. 4 is a perspective view illustrating a state in which a part of the mobile terminal charging device illustrated in FIG. 2 is omitted.

FIG. 5 is a plan view illustrating the mobile terminal charging device in the state illustrated in FIG. 4.

FIG. 6 is a sectional view taken along the dashed line VI-VI in the mobile terminal charging device illustrated in FIG. 2.

FIG. 7 is a perspective view illustrating another state of the mobile terminal charging device illustrated in FIG. 4.

FIG. 8 is a plan view illustrating the mobile terminal charging device in the state illustrated in FIG. 7.

FIG. 9 is a control block diagram of the mobile terminal charging device illustrated in FIG. 2.

FIG. 10 is a sectional view illustrating a configuration of a support plate of the mobile terminal charging device illustrated in FIG. 2.

FIG. 11 is a plan view illustrating a configuration of the support plate of the mobile terminal charging device illustrated in FIG. 2.

FIG. 12 is a perspective view illustrating a detection coil of the mobile terminal charging device illustrated in FIG. 2.

FIG. 13 is a plan view illustrating the detection coil of the mobile terminal charging device illustrated in FIG. 2.

FIG. 14 is a diagram illustrating an operation of the mobile terminal charging device illustrated in FIG. 2.

FIG. 15 is a diagram illustrating an operation of the mobile terminal charging device illustrated in FIG. 2.

FIG. 16 is a diagram illustrating an operation of the mobile terminal charging device illustrated in FIG. 2.

FIG. 17 is a diagram illustrating an operation of the mobile terminal charging device illustrated in FIG. 2.

FIG. 18 is a diagram illustrating an operation of the mobile terminal charging device illustrated in FIG. 2.

FIG. 19 is a flowchart illustrating an operation of the mobile terminal charging device illustrated in FIG. 2.

FIG. 20 is a diagram illustrating a relationship between a location where the charging coil is present and a resonance frequency of a foreign object detection coil.

FIG. 21 is a diagram illustrating a relationship between a location where the charging coil is present and a resonance voltage of the foreign object detection coil.

FIG. 22 is a diagram illustrating a resonance frequency of the foreign object detection coil in a case where a metal foreign object is present.

FIG. 23 is a diagram illustrating a resonance voltage of the foreign object detection coil in a case where a metal foreign object is present.

FIG. 24 is a diagram illustrating an operation of the mobile terminal charging device illustrated in FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Prior to description of an exemplary embodiment of the present invention, problems of the above-described example of the related art will be described. In the example of the related art, the position detection means detects a position of a mobile terminal placed on the upper surface of the support plate, the charging coil is moved to the position detected by the position detection means, and charging is performed in this state. Such a mobile terminal charging device has the following problems.

In other words, in a state in which there is a foreign object such as a coin on the upper surface of the support plate, if a user places a mobile terminal thereon, there is a case where charging is started despite the presence of the foreign object. Consequently, a magnetic flux from the charging coil is also supplied to the foreign object, and thus there is a problem in that the temperature of the foreign object increases.

Therefore, there is a technique in which a metal foreign object is detected by using foreign object detection means, and charging is not started. For example, the foreign object detection means includes a foreign object detection coil and an oscillation circuit connected thereto, and detects a foreign object by using a change in an oscillation state of the oscillation circuit if the metal foreign object is present.

However, in a mobile terminal charging device including a charging coil movably provided, there is a case where the movable charging coil greatly influences an oscillation circuit of foreign object detection means, and thus the foreign object detection means cannot detect a metal foreign object. Consequently, since charging is started despite the presence of the foreign object, and a magnetic flux from the charging coil is also supplied to the foreign object, the temperature of the foreign object increases.

Hereinafter, with reference to the drawings, a description will be made of an example in which a mobile terminal charging device according to an exemplary embodiment of the present invention is equipped in a vehicle.

(Exemplary Embodiment 1)

In FIG. 1, steering wheel 3 is provided on the front side in vehicle interior 2 of vehicle 1. Electronic apparatus 4 which reproduces music or videos and displays car navigation images and the like is provided on the lateral side of steering wheel 3. Mobile terminal charging device 5 is provided on the rear side of electronic apparatus 4 in vehicle interior 2.

Mobile terminal charging device 5 includes, as illustrated in FIGS. 2 to 8, box-shaped main body case 7 in which support plate 6 is disposed on an upper surface thereof, and charging coil 8 provided to be moved in a horizontal direction in a state of opposing a lower surface side of support plate 6 in main body case 7.

The mobile terminal charging device also includes driver 9 which can cause charging coil 8 to be moved in the horizontal direction so as to oppose the lower surface side of support plate 6, and a controller (the reference numeral 10 in FIG. 9) connected to driver 9 and charging coil 8.

Hereinafter, each constituent element will be described in detail. First, support plate 6 will be described.

As illustrated in FIG. 6, support plate 6 has a configuration in which front surface plate 11, intermediate plate 12, and rear surface plate 13 overlap each other.

Front surface plate 11 and rear surface plate 13 are made of synthetic resin, and intermediate plate 12 is made of ceramics. In other words, a magnetic flux from charging coil 8 can pass through support plate 6 toward mobile terminal 15.

Position detection coil 14 illustrated in FIGS. 10 and 11 is provided in the Y direction and the X direction on front and rear surfaces of intermediate plate 12.

Position detection coil 14 used in PTL 1 detects at which position mobile terminal 15 is placed on the mobile terminal placement portion which is the upper surface of support plate 6 as illustrated in FIG. 3.

In the present exemplary embodiment, position detection coil 14 detects at which position mobile terminal 15 is placed on the upper surface of support plate 6 as illustrated in FIG. 3. Next, driver 9 moves charging coil 8 to a position opposing a terminal charging coil (the reference numeral 15 a in FIG. 14) of mobile terminal 15.

Four foreign object detection coils 55 are disposed in a state of being close to each other in the Y direction on a front surface side (upper surface side) of front surface plate 11. Four foreign object detection coils 55 are disposed in a state of being close to each other in the Y direction on a rear surface side (lower surface side) of rear surface plate 13.

In the present exemplary embodiment, foreign object detection coils 55 detect whether or not there is a foreign object on the front surface side (upper surface side) of front surface plate 11 during non-conduction of charging coil 8. This will be described in detail in the following description of an operation thereof.

Next, charging coil 8 will be described. As illustrated in FIGS. 4 and 5, charging coil 8 has a ring shape formed by winding a wiring material in a spiral shape. An outer peripheral side and a lower surface side of charging coil 8 are held by holding member 16 made of synthetic resin.

Support leg 17 extending toward a lower side of charging coil 8 is integrally formed with holding member 16 on its lower surface by using synthetic resin as illustrated in FIG. 6.

A gap of 0.3 millimeters is provided between a lower surface of support leg 17 and an upper surface of metallic support plate 18 disposed under support leg 17. Therefore, in a normal state, the lower surface of support leg 17 is not in contact with the upper surface of support plate 18 during movement of charging coil 8.

Control board 19 and lower plate 20 of main body case 7 are disposed under support plate 18. Support member 21 penetrating through control board 19 is provided between a lower surface of support plate 18 and an upper surface of lower plate 20. In other words, in the present exemplary embodiment, the lower surface side of support plate 18 is supported by lower plate 20 of main body case 7 via support member 21 in order to increase the strength relative to excessive weight.

Next, driver 9 will be described. As illustrated in FIGS. 4 and 5, driver 9 includes X-axis direction driving shaft 22 and Y-axis direction driving shaft 23. An intermediate portion of each of X-axis direction driving shaft 22 and Y-axis direction driving shaft 23 is in contact with portions other than a portion of holding member 16 holding the charging coil.

In other words, a penetration hole (not illustrated) through which X-axis direction driving shaft 22 penetrates and penetration hole 24 through which Y-axis direction driving shaft 23 penetrates are provided in holding member 16 with a predetermined gap in the vertical direction in a state of crossing each other. X-axis direction driving shaft 22 and Y-axis direction driving shaft 23 are in contact with each other at penetration hole 24.

Worm wheel 25 is provided at one end side of X-axis direction driving shaft 22, gear 26 is provided at one end side thereof, and gear 26 is also provided at the other end side thereof.

Worm wheel 25 is engaged with worm 27, and worm 27 is connected to motor 28.

Gears 26 on both sides are respectively engaged with gear plates 29.

Therefore, if motor 28 is driven, worm 27 is rotated, and thus worm wheel 25 is moved in the X axis direction along with X-axis direction driving shaft 22. Charging coil 8 integrated with X-axis direction driving shaft 22 is moved in the X axis direction.

Worm wheel 30 is provided at one end side of Y-axis direction driving shaft 23, gear 31 is provided at one end side thereof, and gear 31 is also provided at the other end side thereof. Worm wheel 30 is engaged with worm 32, and worm 32 is connected to motor 33. Gears 31 on both sides are respectively engaged with gear plates 34.

Therefore, if motor 33 is driven, worm 32 is rotated, and thus worm wheel 30 is moved in the Y axis direction along with Y-axis direction driving shaft 23. Charging coil 8 integrated with Y-axis direction driving shaft 23 is moved in the Y axis direction.

Flexible wiring 35 illustrated in FIG. 4 causes a current to flow through charging coil 8. An end of flexible wiring 35 is fixed to the side surface of above-described support leg 17.

As illustrated in FIG. 9, controller 10 is connected to motor 28 via X-axis motor controller 36, and is connected to motor 33 via Y-axis motor controller 37.

For example, stepping motors are used as motors 28 and 33, and thus controller 10 can detect a position of charging coil 8. This will be described later.

Controller 10 is connected to charging coil 8 via charging coil controller 38, and is also connected to position detection coil 14 via position detection coil controller 39.

Next, a description will be made of a procedure of detecting whether or not there is a foreign object on the front surface side (upper surface side) of front surface plate 11 during conduction of charging coil 8. In the present exemplary embodiment, as described above, foreign object detection coil 55 detects whether or not there is a foreign object on the front surface side (upper surface side) of front surface plate 11 during non-conduction of charging coil 8. On the other hand, during conduction of charging coil 8, the presence of a foreign object is detected by large diameter detection coil 43 illustrated in FIGS. 12 and 13 provided between charging coil 8 and the mobile terminal placement portion of support plate 6, and detection coil 44 which is disposed inside detection coil 43 and has a smaller diameter than that of detection coil 43.

Specifically, in the present exemplary embodiment, charging coil 8 is movable depending on a location where mobile terminal 15 is placed. Therefore, detection coils 43 and 44 are disposed on the upper surface of charging coil 8 (the lower surface of support plate 6) and are movable along with charging coil 8.

Large diameter detection coil 43 has nearly the same size as the outer diameter of annular charging coil 8 (the detection coil is slightly smaller than the outer diameter of charging coil 8), and small diameter detection coil 44 has nearly the same size as the inner diameter of annular charging coil 8 (the detection coil is slightly larger than the inner diameter of charging coil 8).

As illustrated in FIG. 9, large diameter detection coil 43 and small diameter detection coil 44 are connected to controller 10 via voltage detectors 45 and 46, respectively.

Memory 47 illustrated in FIG. 9 stores a program or the like for performing a safety operation on metal foreign objects by using large diameter detection coil 43 and small diameter detection coil 44.

In the present exemplary embodiment, if a metal foreign object is present between the mobile terminal placement portion (the upper surface of support plate 6) and mobile terminal 15, it is found that a magnetic flux in the inner portion of charging coil 8 decreases, and, conversely, magnetic fluxes in other portions increase, and this state is detected by large diameter detection coil 43 and small diameter detection coil 44.

Hereinafter, first, this operation will be described with reference to FIGS. 13 to 18 illustrating the operation in a simplified manner.

FIG. 14 illustrates a state in which mobile terminal 15 is being charged in a state in which there is no metal foreign object between the mobile terminal placement portion (the upper surface of support plate 6) and mobile terminal 15.

In FIGS. 13 to 18, magnetic body 48 is provided on a lower side (an opposite side to mobile terminal 15) of charging coil 8 and forms a magnetic path. Magnetic body 49 is provided on an upper side (an opposite side to mobile terminal charging device 5) of terminal charging coil 15 a and forms a magnetic path.

During charging, as illustrated in FIG. 14, a magnetic flux from charging coil 8 of mobile terminal charging device 5 is supplied to terminal charging coil 15 a of mobile terminal 15. This magnetic flux induces a voltage in terminal charging coil 15 a, and thus mobile terminal 15 is charged.

The magnetic flux having passed through terminal charging coil 15 a returns to charging coil 8 via magnetic body 49, a space, and magnetic body 48 as indicated by arrows.

In contrast, FIG. 15 illustrates a state in which mobile terminal 15 is being charged in a state in which non-magnetic metal foreign object 50 (for example, a coin made of aluminum) is present between the mobile terminal placement portion (the upper surface of support plate 6) and mobile terminal 15.

In this case, as illustrated in FIG. 15, an eddy current is induced in metal foreign object 50 by a magnetic flux passing through metal foreign object 50. As a result, a magnetic flux induced by the eddy current is generated.

As mentioned above, the magnetic flux induced by the eddy current has a direction opposite to a direction of a magnetic flux directed from charging coil 8 toward terminal charging coil 15 a in an inner portion of metal foreign object (the central direction of charging coil 8). The magnetic flux induced by the eddy current has the same direction as the direction of the magnetic flux directed from charging coil 8 toward terminal charging coil 15 a in other portions (a direction opposite to the center of charging coil 8).

As a result, as illustrated in FIG. 16, among the magnetic fluxes directed from charging coil 8 toward terminal charging coil 15 a, a magnetic flux advancing in the direction through the inner side of charging coil 8 is curved outward from the inner side portion of charging coil 8 and is then directed toward terminal charging coil 15 a. In other words, the magnetic flux in the inner side portion of charging coil 8 decreases, and, conversely, the magnetic flux in the outer side portion of charging coil 8 increases.

In the present exemplary embodiment, the distribution state of the magnetic fluxes illustrated in FIG. 16 can be detected by detection coils 43 and 44. Specifically, a first voltage (V1) detected by large diameter detection coil 43 increases (as a result of there being a large number of magnetic fluxes, and a distance to the magnetic fluxes also becoming short), and, conversely, a second voltage (V2) detected by small diameter detection coil 44 decreases (as a result of there being a small number of magnetic fluxes, and a distance to the magnetic fluxes also becoming long).

In the present exemplary embodiment, a peak voltage of the first voltage (V1) detected by large diameter detection coil 43 is detected by voltage detector 45, and a peak voltage of the second voltage (V2) detected by small diameter detection coil 44 is detected by voltage detector 46. Controller 10 compares the ratio (V2/V1) of the second voltage (V2) to the first voltage (V1) with a set value (which is stored in memory 47 and is, for example, 0.7), and performs a safety operation on the basis of a comparison result.

As an example, in the state (the presence of metal foreign object 50) illustrated in FIG. 16, the second voltage (V2) detected by small diameter detection coil 44 is, for example, 25% smaller than in the state (the absence of metal foreign object 50) illustrated in FIG. 14. In contrast, in the state (the presence of metal foreign object 50) illustrated in FIG. 16, the first voltage (V1) detected by large diameter detection coil 43 is, for example, 170% larger than in the state (the absence of metal foreign object 50) illustrated in FIG. 14. As a result, the ratio (V2/V1) of the second voltage (V2) to the first voltage (V1) is reduced by half or less (0.5 or less) in the state (the presence of metal foreign object 50) illustrated in FIG. 16 compared with the state (the absence of metal foreign object 50) illustrated in FIG. 14.

Since the detected value (0.5 or less) is sufficiently smaller than the set value (0.7) stored in memory 47, controller 10 detects the presence of metal foreign object 50 so as to instantly stop the supply of a current to charging coil 8, and operates alarm 51 illustrated in FIGS. 2 and 9. In other words, alarm 51 is connected to controller 10 as illustrated in FIG. 9, and performs a notification of an abnormal state with a light when metal foreign object 50 is present.

Next, FIG. 17 illustrates a state in which mobile terminal 15 is being charged in a state in which magnetic metal foreign object 52 (for example, an iron substance) is present between the mobile terminal placement portion (the upper surface of support plate 6) and mobile terminal 15. Also in this case, as illustrated in FIG. 17, an eddy current is induced in metal foreign object 52 by a magnetic flux passing through metal foreign object 52. As a result, a magnetic flux excited by the eddy current is generated.

Metal foreign object 52 here is a magnetic body, and magnetic fluxes advancing into metal foreign object 52 include magnetic fluxes passing therethrough and magnetic fluxes advancing thereinto for example, outward. Therefore, FIG. 17 illustrates the additional magnetic flux caused by the eddy current, unlike FIG. 15.

However, the magnetic flux which is additionally generated in this way has a direction opposite to the direction of the magnetic flux directed from charging coil 8 toward terminal charging coil 15 a in an inner portion thereof (the central direction of charging coil 8). The magnetic flux has the same direction as the direction of the magnetic flux directed from charging coil 8 toward terminal charging coil 15 a in an outer portion (a direction opposite to the center of charging coil 8) of the magnetic flux.

As a result, as illustrated in FIG. 18, among the magnetic fluxes directed from charging coil 8 toward terminal charging coil 15 a, a magnetic flux advancing in the direction through the inner side of charging coil 8 is curved outward from the inner side portion of charging coil 8 and is then directed toward terminal charging coil 15 a (some magnetic fluxes advance into metal foreign object 52 in the outer side thereof). In other words, the magnetic flux in the inner side portion of charging coil 8 decreases, and the magnetic flux in the outer side portion of charging coil 8 increases.

This situation can be detected by large diameter detection coil 43 and small diameter detection coil 44 disposed on the upper surface side (terminal charging coil 15 a side) of charging coil 8.

Specifically, the first voltage (V1) detected by large diameter detection coil 43 increases (as a result of there being a large number of magnetic fluxes, and a distance to the magnetic fluxes also becoming short), and, conversely, the second voltage (V2) detected by small diameter detection coil 44 decreases (as a result of there being a small number of magnetic fluxes, and a distance to the magnetic fluxes also becoming long).

A peak voltage of the first voltage (V1) detected by large diameter detection coil 43 is detected by voltage detector 45, and a peak voltage of the second voltage (V2) detected by small diameter detection coil 44 is detected by voltage detector 46. Controller 10 compares the ratio (V2/V1) of the second voltage (V2) to the first voltage (V1) with a set value (which is stored in memory 47 and is, for example, 0.7), and performs a safety operation on the basis of a comparison result.

As an example, in the state (the presence of metal foreign object 52) illustrated in FIG. 17, the second voltage (V2) detected by small diameter detection coil 44 is, for example, 15% smaller than in the state (the absence of metal foreign object 52) illustrated in FIG. 14. In contrast, in the state (the presence of metal foreign object 52) illustrated in FIG. 17, the first voltage (V1) detected by large diameter detection coil 43 is, for example, 170% larger than in the state (the absence of metal foreign object 52) illustrated in FIG. 14. As a result, the ratio (V2/V1) of the second voltage (V2) to the first voltage (V1) is reduced by half or less (0.5 or less) in the state (the presence of metal foreign object 52) illustrated in FIG. 17 compared with the state (the absence of metal foreign object 52) illustrated in FIG. 14.

Since the detected value (0.5 or less) is sufficiently smaller than the set value (0.7) stored in memory 47, controller 10 detects the presence of metal foreign object 52 so as to instantly stop the supply of a current to charging coil 8, and operates alarm 51 illustrated in FIGS. 2 and 9. In other words, controller 10 lights alarm 51 so as to perform a notification of an abnormal state.

As described above, in the present exemplary embodiment, even if either of non-magnetic metal foreign object 50 and magnetic metal foreign object 52 is present between the mobile terminal placement portion (the upper surface of support plate 6) and mobile terminal 15, it is found that a magnetic flux in the inner portion of charging coil 8 decreases, and, conversely, magnetic fluxes in other portions increase, and this state is detected by large diameter detection coil 43 and small diameter detection coil 44.

In other words, in a case where large diameter detection coil 43 detects an increase in the outer magnetic flux, the first voltage (V1) increases. If the inner magnetic flux decreases, the second voltage (V2) detected by small diameter detection coil 44 inversely decreases. Therefore, the ratio (V2/V1) between both voltages is sufficiently smaller than the set value. Thus, controller 10 can reliably detect the presence of metal foreign object 50 or 52, and can reliably perform a safety operation.

An operation of detecting metal foreign object 50 or 52 (determination based on the ratio V2/V1) is not substantially influenced by whether the metal foreign object is a magnetic body or a non-magnetic body, or the type of charged mobile terminal 15. Therefore, the mobile terminal charging device can charge various mobile terminals 15 with versatility and is considerably convenient to use. In the present exemplary embodiment, a safety operation is performed on the basis of a comparison result of a voltage ratio (V2/V1) and a set value by using the first voltage (V1) detected by large diameter detection coil 43 and the second voltage (V2) detected by small diameter detection coil 44. However, an exemplary embodiment of the present invention is not limited to such a configuration. For example, there may be a configuration in which a safety operation is performed on the basis of a comparison result of the ratio (V1/V2) of the first voltage to the second voltage and a set value. In this case, in a case where the voltage ratio (V1/V2) is more than the set value, the safety operation is performed.

In the present exemplary embodiment, a description has been made of an example in which mobile terminal charging device 5 is provided in vehicle interior 2 of vehicle 1. This is because a coin or the like is frequently placed on support plate 6 in vehicle 1.

In other words, in vehicle 1, mobile terminal 15 is deviated from the upper surface of support plate 6 due to inertia of an advancing direction or vibration during driving of the vehicle. Thus, as a countermeasure therefor, as illustrated in FIG. 3, guard portion 53 protruding upward from support plate 6 is provided at the peripheral portion of support plate 6. As a result, a state occurs in which a coin hardly falls off during driving of the vehicle, and this causes the coin to be placed on support plate 6. Therefore, it is very useful to provide mobile terminal charging device 5 of the present exemplary embodiment in vehicle interior 2 of vehicle 1.

In the present exemplary embodiment, a description has been made of an example in which large diameter detection coil 43 and small diameter detection coil 44 are provided on the upper surface side of charging coil 8 (terminal charging coil 15 a side), but, as illustrated in FIGS. 12 and 13, there may be a configuration in which intermediate diameter detection coil 54 is provided between large diameter detection coil 43 and small diameter detection coil 44 and is also connected to controller 10.

In other words, if intermediate diameter detection coil 54 is provided, switching between the detection coils 43, 44 and 54 for comparison can be performed, or situations between detection coils 43 and 54, and 54 and 44 can be detected.

Detection coil 43 and detection coil 44 are not limited to circular shapes. In other words, as long as a magnetic flux change can be converted into a voltage, an elliptical coil, a rectangular coil whose corner portion is arced, or the like may be used as a detection coil.

As described above, in the present exemplary embodiment, foreign object detection coils 55 detect whether or not there is a foreign object on the front surface side (upper surface side) of front surface plate 11 during non-conduction of charging coil 8. Next, an operation thereof will be described in detail. In the above-described configuration, if power switch 40 illustrated in FIGS. 2 and 9 is turned on (step S1 in FIG. 19), a position of charging coil 8 is initialized (step S2 in FIG. 19).

The position initialization indicates that controller 10 drives motors 28 and 33 via X-axis motor controller 36 and Y-axis motor controller 37 so as to return charging coil 8 to the corner (coordinates xo and yo) illustrated in FIG. 7. In other words, if charging coil 8 is moved to the corner inside main body case 7 provided with switches 41 and 42, switches 41 and 42 are operated, and thus controller 10 determines that a position of charging coil 8 has been initialized.

Controller 10 supplies detection pulses to the above-described eight foreign object detection coils 55, respectively. In a case where a resonance frequency of each of foreign object detection coils 55 is lower than a reference resonance frequency, stored in memory 47, for each location where charging coil 8 is present, or a resonance voltage detected by each foreign object detection coil 55 is higher than a reference resonance voltage, stored in memory 47, for each location where charging coil 8 is present, controller 10 performs a safety operation (steps S3 and S4 in FIG. 19).

In relation to detailed description thereof, FIG. 20 illustrates a state in which a resonance frequency of corresponding foreign object detection coil 55 is influenced by a location where charging coil 8 is present. Specifically, line A of FIG. 20 indicates resonance frequencies of respective foreign object detection coils 55 when charging coil 8 is present at coordinates (10,0), and indicates a situation in which resonance frequencies of foreign object detection coils 55 near charging coil 8 are lowered. Line B of FIG. 20 indicates resonance frequencies of respective foreign object detection coils 55 when charging coil 8 is present at coordinates (10,35), and indicates a situation in which resonance frequencies of foreign object detection coils 55 near charging coil 8 are lowered.

Line A of FIG. 21 indicates resonance voltages of respective foreign object detection coils 55 when charging coil 8 is present at coordinates (10,0), and indicates a situation in which resonance voltages of foreign object detection coils 55 near charging coil 8 are heightened. Line B of FIG. 21 indicates resonance voltages of respective foreign object detection coils 55 when charging coil 8 is present at coordinates (10,35), and indicates a situation in which resonance voltages of foreign object detection coils 55 near charging coil 8 are heightened. In other words, it has been found that a resonance frequency of foreign object detection coil 55 near charging coil 8 is lowered, and, conversely, a resonance voltage of foreign object detection coil 55 near charging coil 8 is heightened.

Line A of FIG. 22 indicates resonance frequencies of respective foreign object detection coils 55 in a case where a metal foreign object is absent when charging coil 8 is present at coordinates (10,0). Line B of FIG. 22 indicates resonance frequencies of respective foreign object detection coils 55 in a case where a metal foreign object is present at fourth foreign object detection coil 55 when charging coil 8 is present at coordinates (10,0), and indicates a situation in which resonance frequencies of foreign object detection coils 55 near charging coil 8 are heightened.

Line A of FIG. 23 indicates resonance voltages of respective foreign object detection coils 55 in a case where a metal foreign object is absent when charging coil 8 is present at coordinates (10,0). Line B of FIG. 23 indicates resonance voltages of respective foreign object detection coils 55 in a case where a metal foreign object is present at fourth foreign object detection coil 55 when charging coil 8 is present at coordinates (10,0), and indicates a situation in which resonance voltages of foreign object detection coils 55 near charging coil 8 are lowered.

In other words, it has been found that a resonance frequency of foreign object detection coil 55 near the metal foreign object is heightened, and, conversely, a resonance voltage of foreign object detection coil 55 near the metal foreign object is lowered.

In the present exemplary embodiment, a metal foreign object is detected by foreign object detection coil 55 during non-conduction of charging coil 8 on the basis of such a phenomenon.

Specifically, memory 47 stores a reference resonance frequency and a reference resonance voltage of each foreign object detection coil 55 for each location where charging coil 8 is present. In this state, first, controller 10 detects that charging coil 8 has returned to the corner (coordinates xo and yo) illustrated in FIG. 7 by using switches 41 and 42. Consequently, controller 10 can detect a location where charging coil 8 is present.

In the present exemplary embodiment, as illustrated in FIG. 24, in a state in which power switch 40 is turned on, during non-conduction of charging coil 8, foreign object detection performed by foreign object detection coil 55 and position detection of charging coil 8 performed by position detection coil 14 are alternately repeatedly performed.

As illustrated in FIGS. 22 and 23, if resonance frequencies detected by eight foreign object detection coils 55 are higher than the resonance frequencies stored in memory 47 in advance by a predetermined value or more, or resonance voltages detected by eight foreign object detection coils 55 are lower than the resonance voltages stored in memory 47 in advance by a predetermined value or more, controller 10 identifies the presence of a foreign object. If the presence of the foreign object is identified, controller 10 causes alarm 51 to perform a safety operation (steps S3 and S4 in FIG. 19).

The safety operation during non-conduction of charging coil 8 is performed by alarm 51, but, there may be a configuration in which, if the metal foreign object is not removed thereafter, conduction of charging coil 8 cannot be performed.

Next, in a case where mobile terminal 15 is placed at any position of the mobile terminal placement portion which is the upper surface of support plate 6 as illustrated in FIG. 3, position detection coil 14 detects a location where mobile terminal 15 is placed (step S5 in FIG. 19).

Next, driver 9 moves charging coil 8 to the location (step S6 in FIG. 19). Next, controller 10 performs conduction of charging coil 8 (step S7 in FIG. 19), and a foreign object detection operation in large diameter detection coil 43 and small diameter detection coil 44 provided on the upper surface side of charging coil 8 (terminal charging coil 15 a side) (step S8 in FIG. 19).

If a metal foreign object is detected during charging, controller 10 issues a warning with alarm 51 and stops charging using charging coil 8 as a safety operation (step S9 in FIG. 19).

Since next mobile terminal 15 is subsequently placed on the upper surface of support plate 6 in a state in which charging is finished (step S10 in FIG. 19), herein, a position of charging coil 8 is stored in memory 47 (step S11 in FIG. 19), and charging is finished (step S12 in FIG. 19).

In other words, since conduction of charging coil 8 is not performed in this state, foreign object detection performed by foreign object detection coil 55 and position detection of charging coil 8 performed by position detection coil 14 are alternately repeatedly performed in a charging stop state after the charging as illustrated in FIG. 24.

As is clear from the above description, since it is important that a position of charging coil 8 be specified in order to detect a foreign object, the position of charging coil 8 is stored in memory 47 (step S11 in FIG. 19) and charging is finished (step S12 in FIG. 19).

In other words, since resonance frequencies or resonance voltages of eight foreign object detection coils 55 are influenced by a position of charging coil 8, information corresponding to the position of charging coil 8 is read from memory 47, and appropriate foreign object detection is performed on the basis of the read information.

As mentioned above, in mobile terminal charging device 5, first, controller 10 detects a location where charging coil 8 is present. Next, controller 10 detects a foreign object by using a plurality of foreign object detection coils 55. Then, in a case where a resonance frequency of each of foreign object detection coils 55 is higher than a reference resonance frequency, stored in memory 47, for each location where charging coil 8 is present, or in a case where a resonance voltage detected by each foreign object detection coil 55 is lower than a reference resonance voltage, stored in memory 47, for each location where charging coil 8 is present, controller 10 performs a safety operation.

Therefore, for example, a user removes a foreign object according to a warning issued from alarm 51 as an example of a safety operation, and, as a result, it is possible to prevent an increase in the temperature of the foreign object.

Conduction of charging coil 8 can be stopped during issuance of a warning from alarm 51, and, also in the above-described manner, it is possible to prevent an increase in the temperature of the foreign object.

As described above, in an aspect of the present invention, there is a configuration in which, first, the controller detects a location where the charging coil is present; next, the controller detects a foreign object by using a plurality of foreign object detection coils; and, then, in a case where a resonance frequency of each of the foreign object detection coils is higher than a reference resonance frequency, stored in the memory, for each location where the charging coil is present, or in a case where a resonance voltage detected by each foreign object detection coil is lower than a reference resonance voltage, stored in the memory, for each location where the charging coil is present, the controller performs a safety operation.

Therefore, for example, a user removes a foreign object according to a warning (an example of a safety operation) as foreign object alarming means, and, as a result, it is possible to prevent an increase in the temperature of the foreign object.

Conduction of the charging coil can be stopped during issuance of a warning as foreign object alarming means, and, also in the above-described manner, it is possible to prevent an increase in the temperature of the foreign object.

Therefore, the mobile terminal charging device is expected as an on-vehicle charging device or a household charging device. 

The invention claimed is:
 1. A mobile terminal charging device comprising: a support plate in which a mobile terminal placement portion is provided on a front surface side of the support plate; a charging coil that is movably disposed in a state of opposing a rear surface side of the support plate; a driver that can move the charging coil on the rear surface side of the support plate; a controller that is connected to the charging coil and the driver; a memory that is connected to the controller; and a plurality of foreign object detection coils that are provided on the support plate and are connected to the controller, wherein the memory stores a reference resonance frequency or a reference resonance voltage of each of the plurality of foreign object detection coils for each location where the charging coil is present, and wherein the controller compares a resonance frequency or a resonance voltage of each of the plurality of foreign object detection coils with the reference resonance frequency or the reference resonance voltage corresponding to a position of the charging coil, and performs a safety operation on the basis of a comparison result.
 2. The mobile terminal charging device of claim 1, wherein, in a case where any one of resonance frequencies of the plurality of foreign object detection coils is higher than the reference resonance frequency, stored in the memory, for each location where the charging coil is present, or a resonance voltage detected by any one of the plurality of foreign object detection coils is lower than the reference resonance voltage, stored in the memory, for each location where the charging coil is present, the controller performs the safety operation.
 3. The mobile terminal charging device of claim 1, wherein the plurality of foreign object detection coils are provided on front and rear surfaces of the support plate.
 4. The mobile terminal charging device of claim 1, further comprising: an alarm that issues a warning in the safety operation.
 5. The mobile terminal charging device of claim 4, wherein conduction of the charging coil is stopped during the safety operation. 